net/core/gen_estimator.c

   1 /*
   2  * net/sched/gen_estimator.c    Simple rate estimator.
   3  *
   4  *              This program is free software; you can redistribute it and/or
   5  *              modify it under the terms of the GNU General Public License
   6  *              as published by the Free Software Foundation; either version
   7  *              2 of the License, or (at your option) any later version.
   8  *
   9  * Authors:     Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>
  10  *              Eric Dumazet <edumazet@google.com>
  11  *
  12  * Changes:
  13  *              Jamal Hadi Salim - moved it to net/core and reshulfed
  14  *              names to make it usable in general net subsystem.
  15  */
  16
  17 #include <linux/uaccess.h>
  18 #include <linux/bitops.h>
  19 #include <linux/module.h>
  20 #include <linux/types.h>
  21 #include <linux/kernel.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/string.h>
  24 #include <linux/mm.h>
  25 #include <linux/socket.h>
  26 #include <linux/sockios.h>
  27 #include <linux/in.h>
  28 #include <linux/errno.h>
  29 #include <linux/interrupt.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/skbuff.h>
  32 #include <linux/rtnetlink.h>
  33 #include <linux/init.h>
  34 #include <linux/slab.h>
  35 #include <linux/seqlock.h>
  36 #include <net/sock.h>
  37 #include <net/gen_stats.h>
  38
  39 /* This code is NOT intended to be used for statistics collection,
  40  * its purpose is to provide a base for statistical multiplexing
  41  * for controlled load service.
  42  * If you need only statistics, run a user level daemon which
  43  * periodically reads byte counters.
  44  */
  45
  46 struct net_rate_estimator {
  47         struct gnet_stats_basic_packed  *bstats;
  48         spinlock_t              *stats_lock;
  49         seqcount_t              *running;
  50         struct gnet_stats_basic_cpu __percpu *cpu_bstats;
  51         u8                      ewma_log;
  52         u8                      intvl_log; /* period : (250ms << intvl_log) */
  53
  54         seqcount_t              seq;
  55         u32                     last_packets;
  56         u64                     last_bytes;
  57
  58         u64                     avpps;
  59         u64                     avbps;
  60
  61         unsigned long           next_jiffies;
  62         struct timer_list       timer;
  63         struct rcu_head         rcu;
  64 };
  65
  66 static void est_fetch_counters(struct net_rate_estimator *e,
  67                                struct gnet_stats_basic_packed *b)
  68 {
  69         memset(b, 0, sizeof(*b));
  70         if (e->stats_lock)
  71                 spin_lock(e->stats_lock);
  72
  73         __gnet_stats_copy_basic(e->running, b, e->cpu_bstats, e->bstats);
  74
  75         if (e->stats_lock)
  76                 spin_unlock(e->stats_lock);
  77
  78 }
  79
  80 static void est_timer(struct timer_list *t)
  81 {
  82         struct net_rate_estimator *est = from_timer(est, t, timer);
  83         struct gnet_stats_basic_packed b;
  84         u64 rate, brate;
  85
  86         est_fetch_counters(est, &b);
  87         brate = (b.bytes - est->last_bytes) << (10 - est->ewma_log - est->intvl_log);
  88         brate -= (est->avbps >> est->ewma_log);
  89
  90         rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log);
  91         rate -= (est->avpps >> est->ewma_log);
  92
  93         write_seqcount_begin(&est->seq);
  94         est->avbps += brate;
  95         est->avpps += rate;
  96         write_seqcount_end(&est->seq);
  97
  98         est->last_bytes = b.bytes;
  99         est->last_packets = b.packets;
 100
 101         est->next_jiffies += ((HZ/4) << est->intvl_log);
 102
 103         if (unlikely(time_after_eq(jiffies, est->next_jiffies))) {
 104                 /* Ouch... timer was delayed. */
 105                 est->next_jiffies = jiffies + 1;
 106         }
 107         mod_timer(&est->timer, est->next_jiffies);
 108 }
 109
 110 /**
 111  * gen_new_estimator - create a new rate estimator
 112  * @bstats: basic statistics
 113  * @cpu_bstats: bstats per cpu
 114  * @rate_est: rate estimator statistics
 115  * @lock: lock for statistics and control path
 116  * @running: qdisc running seqcount
 117  * @opt: rate estimator configuration TLV
 118  *
 119  * Creates a new rate estimator with &bstats as source and &rate_est
 120  * as destination. A new timer with the interval specified in the
 121  * configuration TLV is created. Upon each interval, the latest statistics
 122  * will be read from &bstats and the estimated rate will be stored in
 123  * &rate_est with the statistics lock grabbed during this period.
 124  *
 125  * Returns 0 on success or a negative error code.
 126  *
 127  */
 128 int gen_new_estimator(struct gnet_stats_basic_packed *bstats,
 129                       struct gnet_stats_basic_cpu __percpu *cpu_bstats,
 130                       struct net_rate_estimator __rcu **rate_est,
 131                       spinlock_t *lock,
 132                       seqcount_t *running,
 133                       struct nlattr *opt)
 134 {
 135         struct gnet_estimator *parm = nla_data(opt);
 136         struct net_rate_estimator *old, *est;
 137         struct gnet_stats_basic_packed b;
 138         int intvl_log;
 139
 140         if (nla_len(opt) < sizeof(*parm))
 141                 return -EINVAL;
 142
 143         /* allowed timer periods are :
 144          * -2 : 250ms,   -1 : 500ms,    0 : 1 sec
 145          *  1 : 2 sec,    2 : 4 sec,    3 : 8 sec
 146          */
 147         if (parm->interval < -2 || parm->interval > 3)
 148                 return -EINVAL;
 149
 150         est = kzalloc(sizeof(*est), GFP_KERNEL);
 151         if (!est)
 152                 return -ENOBUFS;
 153
 154         seqcount_init(&est->seq);
 155         intvl_log = parm->interval + 2;
 156         est->bstats = bstats;
 157         est->stats_lock = lock;
 158         est->running  = running;
 159         est->ewma_log = parm->ewma_log;
 160         est->intvl_log = intvl_log;
 161         est->cpu_bstats = cpu_bstats;
 162
 163         if (lock)
 164                 local_bh_disable();
 165         est_fetch_counters(est, &b);
 166         if (lock)
 167                 local_bh_enable();
 168         est->last_bytes = b.bytes;
 169         est->last_packets = b.packets;
 170
 171         if (lock)
 172                 spin_lock_bh(lock);
 173         old = rcu_dereference_protected(*rate_est, 1);
 174         if (old) {
 175                 del_timer_sync(&old->timer);
 176                 est->avbps = old->avbps;
 177                 est->avpps = old->avpps;
 178         }
 179
 180         est->next_jiffies = jiffies + ((HZ/4) << intvl_log);
 181         timer_setup(&est->timer, est_timer, 0);
 182         mod_timer(&est->timer, est->next_jiffies);
 183
 184         rcu_assign_pointer(*rate_est, est);
 185         if (lock)
 186                 spin_unlock_bh(lock);
 187         if (old)
 188                 kfree_rcu(old, rcu);
 189         return 0;
 190 }
 191 EXPORT_SYMBOL(gen_new_estimator);
 192
 193 /**
 194  * gen_kill_estimator - remove a rate estimator
 195  * @rate_est: rate estimator
 196  *
 197  * Removes the rate estimator.
 198  *
 199  */
 200 void gen_kill_estimator(struct net_rate_estimator __rcu **rate_est)
 201 {
 202         struct net_rate_estimator *est;
 203
 204         est = xchg((__force struct net_rate_estimator **)rate_est, NULL);
 205         if (est) {
 206                 del_timer_sync(&est->timer);
 207                 kfree_rcu(est, rcu);
 208         }
 209 }
 210 EXPORT_SYMBOL(gen_kill_estimator);
 211
 212 /**
 213  * gen_replace_estimator - replace rate estimator configuration
 214  * @bstats: basic statistics
 215  * @cpu_bstats: bstats per cpu
 216  * @rate_est: rate estimator statistics
 217  * @lock: lock for statistics and control path
 218  * @running: qdisc running seqcount (might be NULL)
 219  * @opt: rate estimator configuration TLV
 220  *
 221  * Replaces the configuration of a rate estimator by calling
 222  * gen_kill_estimator() and gen_new_estimator().
 223  *
 224  * Returns 0 on success or a negative error code.
 225  */
 226 int gen_replace_estimator(struct gnet_stats_basic_packed *bstats,
 227                           struct gnet_stats_basic_cpu __percpu *cpu_bstats,
 228                           struct net_rate_estimator __rcu **rate_est,
 229                           spinlock_t *lock,
 230                           seqcount_t *running, struct nlattr *opt)
 231 {
 232         return gen_new_estimator(bstats, cpu_bstats, rate_est,
 233                                  lock, running, opt);
 234 }
 235 EXPORT_SYMBOL(gen_replace_estimator);
 236
 237 /**
 238  * gen_estimator_active - test if estimator is currently in use
 239  * @rate_est: rate estimator
 240  *
 241  * Returns true if estimator is active, and false if not.
 242  */
 243 bool gen_estimator_active(struct net_rate_estimator __rcu **rate_est)
 244 {
 245         return !!rcu_access_pointer(*rate_est);
 246 }
 247 EXPORT_SYMBOL(gen_estimator_active);
 248
 249 bool gen_estimator_read(struct net_rate_estimator __rcu **rate_est,
 250                         struct gnet_stats_rate_est64 *sample)
 251 {
 252         struct net_rate_estimator *est;
 253         unsigned seq;
 254
 255         rcu_read_lock();
 256         est = rcu_dereference(*rate_est);
 257         if (!est) {
 258                 rcu_read_unlock();
 259                 return false;
 260         }
 261
 262         do {
 263                 seq = read_seqcount_begin(&est->seq);
 264                 sample->bps = est->avbps >> 8;
 265                 sample->pps = est->avpps >> 8;
 266         } while (read_seqcount_retry(&est->seq, seq));
 267
 268         rcu_read_unlock();
 269         return true;
 270 }
 271 EXPORT_SYMBOL(gen_estimator_read);